Do you think that a mink is the traitor? Whoever the traitor is, I hope it will be a good reveal! I think the last "traitor revealed" we got was Pudding but she turned out to be somewhat of a comedy character in the end.
Well I don't really get how/why a mink could have gotten into contact with Orochi. On the other hand it has never been explained how Jack knew exactly that Raizou was on Zou nor how Kinemon, Momo and the others returned. Though, that again contrasts with the reality that most people considered Orochi paranoid and that he didn't seem to have any actual proof of their return.
It pretty much comes down to that Orochi and Kaidou operate quite independently from another and don't share information as much as they should...and this gets kinda confirmed in this chapter as apparently they have an average of meeting each other once a year.
So I'm more inclined to believe it's someone from Wano, in particular because it would be near impossible for a mink to decipher the riddle on the paper (unless it was one of the minks from the inner circle).